type Names = "aaa" | "bbb" | "ccc";

const a: Names = "aaa";

type Numbers = 111 | 222 | 333;
let b: Numbers = 111;
// b = 123; // 报错

type Number2 = 111 | "aaa" | 333 | true;
let c: Number2 = 111;
c = "aaa";
